Method for converting a 17-20, 20-21 bismethylenedioxy or a 17-20, 20-21 bis-substituted methylenedioxy steroid of the pregnane series to a 17alpha, 21-dihydroxy-20-ketosteroid of the pregnane series



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METHQD FOR QQNVERTZNG A 17-20,20-21 BIS- METHYLENEDTGXY OR A 17-20,20-21 BIS-SUB- STITUTED METHYLENEDIOXY STEROID OF THE PREGNANE SERIES TO A 17a,21-DIHY-.

DROXY-Zll-KETU STEROID OF THE PREGNANE SERIES Roger E. Beyier, Westiield, and Lewis H. Sarett, Princeton, N. 5., assignors t Merck & Co, Inc, Rahway, N. 5., a corporation of New Jersey No Drawing. Application January 2, 1957 Serial No. 632,026

12 Claims; (Cl. 260-39145) This invention relates to a process for making steroid compounds. More particularly, it relates to a process vfor elaborating a dihydroxyacetone side chain attached as a Claisen condensation or a Grignard reaction to be carried out on the steroid nucleus without undesirable involvement of the dihydroxyacetone side chain. This side chain is normally at carbon atom 17 of the nucleus and for this reason the discussion of our invention is directed to such steroids. It may, of course, be located at other positions of the nucleus such as at C-16 or C-17a of a D-homo steroid, and the process of our invention is equally applicable to such types of steroids.

It is a purpose of the present invention to provide a process for reforming the dihydroxyacetone side chain from the l7-20,20-21 bismethylenedioxy or 17-20,20-21 bis-substituted methylenedioxy steroid. It is a more specific object to provide a method of treating a 17-20,20-21 bisrnethyle nedioxy (or bis-substituted methylenedioxy) steroid with acid whereby the bisdioxy group is removed and a 17ot,21-d1hYd1'OXY-20-kt0 steroid obtained. A still more definite object is a method of treating a 17-20,- 21 bismethylenedioxy (or bis-substituted methylenedioxy) steroid of the pregnane series with acid, thus forming a 17ot,21-dihydroxy-20-keto-pregnane. Further objects will be evident from the discussion of this process hereinbelow.

Our process may be pictured structurally as follows:

shown. The steroid condensed ring nucleus may be substituted'at one or several of the nuclear carbon atoms .eroid witha suitable aldehyde whereby a 17-20,

' 20-21 bisbutyraldioxy (1t=3), 17-20,20-21 bisvaleral- I 17 20,20 21 bismethylenedioxy 6 meth I Patented Dec. 30, 1958 v 2 and may have one or several nuclear double bonds. The number, nature or location ofsuch nuclear substituents or double bonds does not affect or interfere with the above process for forming the dihydroxyacetone side chain since the rest'of the molecule does not-participate in the reaction. As would be expected, any nuclear substituents subject to acid hydrolysis will be removed but this is not a fundamental molecular change and in most cases is incidental to obtainment of a particular type of steroid.

As will be seenfrom the partial structural formula above, the starting materials for our process are steroidal compounds having twohydrogen atoms or one hydrogen atom and one lower alkyl radical attached to each of two carbon atoms of the bis-dioxy moiety. Such prodnets are made by treating a 17a,21-dihydroxy-20.-keto steroid of the pregnane series with an aldehyde in the presenceof a strong acid. The nature of these substituents depends, therefore, on the particular aldehyde with which the 1704,21-dihYd1'QXY-20-k6t0 moiety has been inactivated. Thus, we may use, and prefer to use, a 17-20,20-21 bismethylenedioxy steroid in which the value of n in the formula above is O, and which is obtained by reaction of the 17a,2l-dihydroxy-ZO-ketone with formaldehyde. Alternatively, a l7-20,20-21 bisethylidenedioxy (n=l), 17- 20,20-2l bispropionaldioxy (12:2), 17-20,-

dioxy (n=4) or a 17-'20,20-21 biscaproaldioxy (n=5) seroid compound of the pregnane series may be obtained with acetaldehyde, propionaldehyde, butyraldehyde, valet aldehyde or caproaldehyde, and employed satisfactorily as starting material for the'process of this inventionQ.

Typical examples of 17-20,2 0- 21 bismethylenedioxy and 17,20,20-2Ibis-substituted methylenedioxy steroids which are converted by our process to l7a,21-dihydroxy-20-l eto steroids are:

17-20,20-2l-bismethylenedioxy-pregnan-3-o1 17- 4,20-21-bismethylenedioxy-4-pregnen-3-one 17-20,20 2l-bismethylenedioxy-4 pregnene-3,1 ledion'e 17- 20,20 21 bismethylenedioxy'- 1,4 pregnadiene- 3,11-dione Y I y 17 20, 20 21 bismethylenedioxy 1,4 pregnadiene- 1 1 9-ol-3-one 17 20,20 21 bisethylidenedioxy 3,1l-dione 17-20-20-21-bisethylidenedioxy-4 pregnene-3 ,1 l-dione l7-20,20-21-bisethylidenedioxy-4-pregnene-1 1,8-ol-3-one l7-20,20-21-bisbutyralidioxy-4-pregnene-3,ll-dione t 17 20,20 21 bisbutyralidoxy 9a, chloro 4 pregnene-11fl-ol-3-one. v 17 -20,20 21 bisvaleraldioxy c bromo 4 pregnene-11fi-ol-3-one 17 20,20 21 bismethylenedioxy 9m fluoro 1,4- pregnadiene-llfi-bl-S-one 17 20,20 21 bismethylenedioxy 12oz fluoro 1,4-

pregnadiene-3,1 l-dione 17,20,20 21 bispropionaldioxy 4 pregnene 6 ol- 3,l1-di0ne 1,4 pregnadiene- .pregnadiene-l 1 8-ol-3-one 17 20, 20 21 bismethylenedioxy 12a chloro 4- pregnene-l lfl-ol-B-one I 17 20,20 21 bismethylenedioxy 4,6 pregnadiene- 3,11-dione 17- 20,20- 21 bismethylenedioxy 9oz fluoro 4 preg- 17 20,20 21 bismethylenedioxy 4 pregnen 9a,1lfldiol-3-one l 17 -20,20-2 1-bismethylenedioxy-alloprcgnane3, 1 l-dione 17 20,20 21 bismethylenedioxy 19 -,nor 4 preg nene-11fi-ol-3-one v l7-20,20-21-bismethylenedioxy-4-pregnen-6-ol-3-one 17 20,20 21 bismethylenedioxy 4,9(11) pregnadien- 3-one 17 20,20 21 bismethylenedioxyw 9,11 oxide 4- pregnen-S-one i 17 20,20 2 1 bis methylenedioxy 1,4 tpreg'nadiene- 3,1l-dione.

17 "0,20 21 bismethylenedioxy -1:4 regame 1 1s- 1 ol-3-one l7,20,20-21biscaproaldioxypregnane-Zs,1l dione l7 20,20 21 bispropionaldioxy- 2 1'' methyl 4 lpregis preferably brought about in a "one-pliasesolvent system.

When an organic acid iscmplo'yed to bring about regeneration or tile dihyd roxyace tone side chain, we find it suitable and convenient to use an excess of the acid asfthels'olyent medium forjthe'reaction. For example, in the conversion of the 17-20,20-21 bismethylenedioxy derivativesof cortisone and hydrocb'rtisone to the parent 1 eb auaasws have use'd aceticandformic acids as both solvent "and acid. Alternatively, a lower aliphatic 'carboiylic acidfsii'eh "as acetic o'r propionic acid, can serve as thef solye ass a stronger acid employed to bring about th'e hydrolysis. Low'er alkanols are another class of satisfactorysolvent's for 'the process. Likewise. a twop hase tench system may be utilized, with the steroid dissolvd il a iiitable water-immiscible organic solvent such "a; "chloroform, methylene chloride, benzene 'and the like. Theoigariic phase and aqueous acidic I pha'se are mixed by agitation to effect the reaction. p

The reaction timesand temperatures are not critical, and optimum conditionswill vary with the particular steroid startin'g.material and acidic reagent employed. Generally, we obtain optimum results at temperatures rangingfrom about 15f C. up to about 100" C., and at*reaction times of about 30 minutes to about 50 hours. We prefer to carry out our process at about 25-75 C. for about three totenhours.

With any particular 17 20,20-2l bismethylenedioxy (or bis-substituted methylenedioxy ste'roid)or acidic reagent the course'of the reaction and the best operating conditions can be easilyand readily de'te'i-mined by an assay with jdianisole bisdiphenylt'etrazolium"chloride, otherwise known as the RT. reagent. With this assay, a 1711,21- dihydroxy ZO-ke'to steroid"will 'give with the B. T. reagent and under the conditions describd byMader et al., Anal. Chem, 24, 666 (1952 "a 'color. The

The 17a,21-dihydroxy-20-keto moiety; either as such or esterified at positions 17 or 2]., is an integral part of intensity of the color, which is easily measurable quahtitatively against a standard solution, 'is a measure of the amount of 1711,21-dihydroxy 20-lteto steroid present 1 since the -l7-20,'20-21 bisdioxy s't'arting rn'aterials of our process do not give a positive test in the B. T, assay.

At the completion 'ef ourprec'eg's, the formedflalldihydroxy-ZO-keto steroid is isolated by any or thefmthods known to. those skilled in the "steroid art. Forexample, the reaction solvent may be removedby concentration and the steroid'ektrhote'd into a water-immiscible organic solvent. The solvent is then removed and the desired compound obtained ineuhs't'antially purefor'm from the residue by chromatography on alumina We prefer to form a C-21 ester of the 'steroidwith a lower aliphatic carboxylic acid after removal of thereaction solvent but prior to any purification steps. These 21- esters, and particularly theacetates, arehighly crystalline compoundsand more readily purified than the free-zlalcohols.

the several steroids which have pronounced cortisone-like activity. The new process described herein is a ready method of reforming this part of the molecule after it has been inactivated or blocked as a 17-20,20-21 bismethylenedioxy-or l7-20,202l bis-substituted methylenedioxy derivative.

The following examples are given for purposes of illustration and not by way of limitation:

, EXAMPLE 1 Cortisone acetate To mg. of l7-20,20-21-bismethylenedioxy-4-pregnene-3,l1-dione is added 5 ml. of methanol and 5 ml. of 5 N sulfuric acid and the heterogeneous mixture refluxed on the steam bath for one hour (homogeneous after 45 minutes). The methanol is removed in vacuo and the resulting aqueous solution thoroughly extracted withethyl acetate. The extract is Washed with sodium bicarbonate, dried and concentrated to give 96 mg. of residue. This is dissolved in 0.3 ml. of pyridine and 0.3 ml. of acetic anhydride. The 'mixture is heated for ten minutes on the steam bath and poured into water. The resultant mixture is extracted several times with methylene chloride, the methylene chloride washed with dilute hydrochloric acid and sodium bicarbonate, dried over magnesium sulfate and evaporated. The residue is recrystallized from acetone to .give cortisone acetate.

EXAMPLE 2 Hydrocortisone acetate To 690 mg. of 17-20,20-21-bismethylenedioxyt-pregnene--ol-3-one is added 50 ml. of 50% acetic acid. This mixture is heated under nitrogen at 100 C. for 6 /3 hours. The reaction mixture is then concentrated under vacuumto dryness. The residue is dissolved in 2.0 ml. of pyridine and 1.8 ml. of acetic anhydride and kept at roomt'emperature for 18 hours. After pouring into water the mixture is extracted several times with methylene chloride. The combined methylene chloride extracts are 'w'asherlwith 2.5 N hydrochloric acid and saturated aqueous sodium bicarbonate. Drying and evaporation of methylene chloride gives'742 mg. of crude hydrocortisone acetate. Chromatography on alumina yields substantially pure hydrocortisone acetate in the etherchloroforin (3 to 7, 2 to 8, and 1 to 9) efiluents.

In the same manner, and using 540 mg. of 17-20,.20- Zl-bismethylenedioxy-l,4-pregnadiene 3,11 dione as starting material, prednisone acetate is obtained.

EXAMPLE 3 Cortisone acetate 200mg. of 17-20,20-21-bismethylenedioxy-4-pregnene- 3,1l-dione in 2.0 ml. of 98-100% formic acid is heated at 80 C. for 20 minutes. After cooling it is poured into about 10 ml. of water and extracted several times with methylene chloride. The combined solvent extracts are washed with saturated sodium bicarbonate solution, dried and concentrated to yield 203 mg. of semicrystalline product. Hydrolysis of this product with sodium methoxide in methanol, followed by acetylation of the hydrolysis product with acetic anhydride-pyridine yields cortisone acetate.

When a mixture of mg. of 17-20,20-21-bismethylenedioxy-1,4-pregnadiene-1lfl-ol-3-one is heated at 75 C. for 30 minutes, and the mixture then worked up as described above, substantially pure prcdnisolone acetate is obtained.

EXAMPLE 4 p l H ydrocortisone added 9.2 mluof 60% perchloric acid. The mixture is EXAMPLE 5 9a -fluoro-cgrtisone To 100 mg. of 17-20,20-21-bismethylenedioxy-9a-fluoro-4-pregnene-3,11-dione in 2.5 ml. of glacial acetic acid is added 0.1 ml. of concentrated hydrochloric acid. After 42 hours at room temperature the reaction is worked up as described in Example 4 to give 9a-tluorocortisone.

EXAMPLE 6 Cortisone acetate To 100 mg. of 17-20,20-21-bismethylenedioxy-4- pregnene-3,ll-dione in 2.5 ml. glacial acetic acid is added 0.2 ml. of concentrated sulfuric acid. After 14 hours at room temperature the mixture is treated as in Example 4. A residue is obtained which on further yields substantially pure cortisone.

EXAMPLE 7 6-dehydr0cortisone acetate A mixture of 200 mg. of 17-20,20-2l-bismethylenedioxy-4-6-pregnadiene-3,1l-dione, 12 ml. of methanol and 12 ml. of 5 N sulfuric acid is refluxed for 90 minutes. The alcohol is removed by concentration in vacuo, and the residual solution extrated with three 10 mL-portions of ethyl acetate. The organic extracts are combined, washed with dilute sodium bicarbonate and dried over magnesium sulfate. The solvent is removed in vacuo leaving a residue which is dissolved in a mixture of 1 ml. of pyridine and 1 ml. of acetic anhydride. After heating on the steam bath for 10 minutes, the mixture is poured into water, and the aqueous phase extracted with three '5 ml.-portions of chloroform. The chloroform solutions are washed with water, acid and base, and dried over magnesium sulfate. On evaporation of the solvent, and crystallization of the residue from acetone, 4-6- pregnadien-l7a,2l-diol-3,l1,20-trione 2 l-acetate is obtained.

EXAMPLE 8 6-methyl prednisone acetate EXAMPLE 9 4,9 (11 -pregnadien-1 70:,21 -dil-3,20-di0ne 21 -acelaze' l0 mg. of 17-2020-21 bisethylidenedioxy-4,9(l l)- pregnadien-3-one is added to 45 ml. of 50% acetic acid and the resulting mixture heated on the steam bath under nitrogen for eight hours. The mixture at the end of this time is concentrated to dryness in vacuo, and the residue dissolved in 3.0 ml. of pyridine and 2.0 ml. of acetic anyhydride. This solution is held at 40 C. for 12 hours and then poured into 30 ml. of water.

The resulting aqueous solution is extracted with three 20 ml.-portions of chloroform, and the combined solvent extracts washed successively with 2 N hydrochloric acid, 5% sodium bicarbonate solution and water. The chloropurification 6 formsolution is dried and concentrated to dryness in vacuo. The residual 4,9(1l)-pregnadien-17a,21-diol-3,20 diQnejZI-acetate may, if desired, be further purifiedby chromatographing on alumina.

EXAMPLE 10 l nllegregr ah-i azz-d a og1,20-rri0ne ZI-acetate Following the procedure of Example 9 with 500 mg. of 17-20,20-21-bispropionaldioxy-allopregnane-3,l l-dione, there is obtained from the chloroform extract allopregnan- 17a,21-diol-3,11,20-trione 2l-acetate.

In the above examples, the starting materials may be prepared by treating a chloroform solution or suspension of a 17a,21-dihydroxy-20-keto steroid appropriately substituted or unsaturated in the nucleus with formaldehyde in the presence of hydrochloric acid to make the 17-20,20- 21bismethylenedioxy compounds, or with a lower alkyl aldehyde in the presence of hydrochloric acid to make the 17-20,20-21 bis-substituted methylenedioxy compounds. The reaction is conveniently conducted at about 30 C. for five hours although for optimum yields the formation of bisdioxy compound is followed by means of the B. T. test referred to above. At the end of the reaction period, the two layers are separated, and the aqueous layer extracted with fresh chloroform. The chloroform solutions are combined, washed with 5% sodium bicarbonate and dried. The chloroform is then removed and the residual bisdioxy steroid further purified, if desired, by recrystalwherein n is a whole integer having a value of 0 to 5 inclusive with an acid selected from the class consisting of perehloric, formic, acetic and mineral acids thereby forming a l7a,2l-dihydroxy-ZO-keto steroid of the pregnane series.

2. The process of claim 1 wherein n is 0.

3. The process of claim 1 wherein n is 1.

4. The process of claim 1 wherein n is 2.

5. The process of claim 1 wherein n is 3.

6. The process which comprises treating a 17-20,20-21 bismethylenedioxy steroid of the pregnane series having at the 3-position a member of the class consisting of keto and hydroxy substituents with an acid selected from the classconsisting of perchloric, formic, acetic and mineral acids thereby forming a l7a,2l-dihydroxy-20-keto steroid of the pregnane series having at the 3-position a member of the class consisting of keto and hydroxy substituents.

7. The process which comprises treating l7-20,20-21 bismethylenedioxy-4-pregnene-3,1l-dione with sulfuric acid thereby forming 4-pregnene-17a,2l-diol-3,l1,20- trione.

8. The process which comprises treating 17-20,20-21 bismethylenedioxy-4-pregnene-11,8-ol-3-one with acetic bismethylenedioxy-1,4-pregn adiene3,11-dione with formic acid thereby forming pred isone.

10. The process which comprises treating 17-20,20-21 bisrnethylenedioxyi-pregnene-11B-ol-3-pne with perchloric acid thereby forming 4-pregnene-11fl,17a;21-tridl-3,20-

dione. t

-11. The process which comprises treating 17-20,20-21 =55 bisethylidenedioxy-4;9( 1 1 -pregnadien-3-one with acetic acid thereby forming 4,9(1'1)'pregnadien-17a,2l-diol- 3,20-dione.

No references cited. 

1. THE PROCESS WHICH COMPRISES TREATING A STERIOD OF THE PREGNANE SERIES HAVING AT CARBON ATOMS 17, 20 AND 21 THE STRUCTURE WHEREIN N IS A WHOLE INTEGER HAVING A VALUE OF 0 TO 5 INCLUSIVE WITH AN ACID SELECTED FROM THE CLASS CONSISTING OF PERCHLORIC, FORMIC, ACETIC AND MINERAL ACIDS THEREBY FORMING A 17A,21-DIHYDROXY-20-KETO STEROID OF THE PREGNANE SERIES. 